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Revision 260 - (hide annotations) (download)
Thu Sep 20 10:19:16 2007 UTC (6 years, 11 months ago) by ph10
File size: 16240 byte(s)
Documentation tidies and clarifications.

1 nigel 41 News about PCRE releases
2     ------------------------
3    
4 ph10 122
5 ph10 260 Release 7.4 21-Sep-07
6 ph10 242 ---------------------
7    
8 ph10 243 The only change of specification is the addition of options to control whether
9 ph10 242 \R matches any Unicode line ending (the default) or just CR, LF, and CRLF.
10 ph10 243 Otherwise, the changes are bug fixes and a refactoring to reduce the number of
11 ph10 242 relocations needed in a shared library.
12    
13    
14 ph10 228 Release 7.3 28-Aug-07
15 ph10 212 ---------------------
16    
17     Most changes are bug fixes. Some that are not:
18    
19     1. There is some support for Perl 5.10's experimental "backtracking control
20     verbs" such as (*PRUNE).
21    
22     2. UTF-8 checking is now as per RFC 3629 instead of RFC 2279; this is more
23     restrictive in the strings it accepts.
24    
25     3. Checking for potential integer overflow has been made more dynamic, and as a
26     consequence there is no longer a hard limit on the size of a subpattern that
27     has a limited repeat count.
28 ph10 227
29     4. When CRLF is a valid line-ending sequence, pcre_exec() and pcre_dfa_exec()
30     no longer advance by two characters instead of one when an unanchored match
31     fails at CRLF if there are explicit CR or LF matches within the pattern.
32 ph10 226 This gets rid of some anomalous effects that previously occurred.
33 ph10 212
34 ph10 227 5. Some PCRE-specific settings for varying the newline options at the start of
35     a pattern have been added.
36 ph10 212
37 ph10 227
38 ph10 184 Release 7.2 19-Jun-07
39 ph10 157 ---------------------
40    
41 ph10 172 WARNING: saved patterns that were compiled by earlier versions of PCRE must be
42 ph10 181 recompiled for use with 7.2 (necessitated by the addition of \K, \h, \H, \v,
43     and \V).
44 ph10 168
45 ph10 159 Correction to the notes for 7.1: the note about shared libraries for Windows is
46     wrong. Previously, three libraries were built, but each could function
47     independently. For example, the pcreposix library also included all the
48     functions from the basic pcre library. The change is that the three libraries
49     are no longer independent. They are like the Unix libraries. To use the
50     pcreposix functions, for example, you need to link with both the pcreposix and
51 ph10 157 the basic pcre library.
52    
53 ph10 166 Some more features from Perl 5.10 have been added:
54 ph10 157
55 ph10 166 (?-n) and (?+n) relative references for recursion and subroutines.
56 ph10 172
57     (?(-n) and (?(+n) relative references as conditions.
58 ph10 182
59 ph10 181 \k{name} and \g{name} are synonyms for \k<name>.
60 ph10 172
61 ph10 168 \K to reset the start of the matched string; for example, (foo)\Kbar
62 ph10 175 matches bar preceded by foo, but only sets bar as the matched string.
63 ph10 182
64     (?| introduces a group where the capturing parentheses in each alternative
65     start from the same number; for example, (?|(abc)|(xyz)) sets capturing
66 ph10 175 parentheses number 1 in both cases.
67 ph10 166
68 ph10 182 \h, \H, \v, \V match horizontal and vertical whitespace, respectively.
69 ph10 166
70 ph10 182
71 ph10 155 Release 7.1 24-Apr-07
72 nigel 93 ---------------------
73    
74 ph10 155 There is only one new feature in this release: a linebreak setting of
75     PCRE_NEWLINE_ANYCRLF. It is a cut-down version of PCRE_NEWLINE_ANY, which
76     recognizes only CRLF, CR, and LF as linebreaks.
77 ph10 122
78 ph10 155 A few bugs are fixed (see ChangeLog for details), but the major change is a
79     complete re-implementation of the build system. This now has full Autotools
80     support and so is now "standard" in some sense. It should help with compiling
81     PCRE in a wide variety of environments.
82    
83 ph10 146 NOTE: when building shared libraries for Windows, three dlls are now built,
84     called libpcre, libpcreposix, and libpcrecpp. Previously, everything was
85     included in a single dll.
86    
87     Another important change is that the dftables auxiliary program is no longer
88 ph10 128 compiled and run at "make" time by default. Instead, a default set of character
89     tables (assuming ASCII coding) is used. If you want to use dftables to generate
90     the character tables as previously, add --enable-rebuild-chartables to the
91     "configure" command. You must do this if you are compiling PCRE to run on a
92     system that uses EBCDIC code.
93 ph10 122
94 ph10 128 There is a discussion about character tables in the README file. The default is
95     not to use dftables so that that there is no problem when cross-compiling.
96    
97    
98 ph10 122 Release 7.0 19-Dec-06
99     ---------------------
100    
101 nigel 93 This release has a new major number because there have been some internal
102     upheavals to facilitate the addition of new optimizations and other facilities,
103     and to make subsequent maintenance and extension easier. Compilation is likely
104     to be a bit slower, but there should be no major effect on runtime performance.
105     Previously compiled patterns are NOT upwards compatible with this release. If
106     you have saved compiled patterns from a previous release, you will have to
107     re-compile them. Important changes that are visible to users are:
108    
109     1. The Unicode property tables have been updated to Unicode 5.0.0, which adds
110     some more scripts.
111    
112     2. The option PCRE_NEWLINE_ANY causes PCRE to recognize any Unicode newline
113     sequence as a newline.
114    
115     3. The \R escape matches a single Unicode newline sequence as a single unit.
116    
117     4. New features that will appear in Perl 5.10 are now in PCRE. These include
118     alternative Perl syntax for named parentheses, and Perl syntax for
119     recursion.
120    
121     5. The C++ wrapper interface has been extended by the addition of a
122     QuoteMeta function and the ability to allow copy construction and
123     assignment.
124    
125     For a complete list of changes, see the ChangeLog file.
126    
127    
128 nigel 91 Release 6.7 04-Jul-06
129     ---------------------
130    
131     The main additions to this release are the ability to use the same name for
132     multiple sets of parentheses, and support for CRLF line endings in both the
133     library and pcregrep (and in pcretest for testing).
134    
135     Thanks to Ian Taylor, the stack usage for many kinds of pattern has been
136     significantly reduced for certain subject strings.
137    
138    
139 nigel 87 Release 6.5 01-Feb-06
140     ---------------------
141    
142     Important changes in this release:
143    
144     1. A number of new features have been added to pcregrep.
145    
146     2. The Unicode property tables have been updated to Unicode 4.1.0, and the
147     supported properties have been extended with script names such as "Arabic",
148     and the derived properties "Any" and "L&". This has necessitated a change to
149     the interal format of compiled patterns. Any saved compiled patterns that
150     use \p or \P must be recompiled.
151    
152     3. The specification of recursion in patterns has been changed so that all
153     recursive subpatterns are automatically treated as atomic groups. Thus, for
154     example, (?R) is treated as if it were (?>(?R)). This is necessary because
155     otherwise there are situations where recursion does not work.
156    
157     See the ChangeLog for a complete list of changes, which include a number of bug
158     fixes and tidies.
159    
160    
161 nigel 77 Release 6.0 07-Jun-05
162     ---------------------
163    
164     The release number has been increased to 6.0 because of the addition of several
165     major new pieces of functionality.
166    
167     A new function, pcre_dfa_exec(), which implements pattern matching using a DFA
168     algorithm, has been added. This has a number of advantages for certain cases,
169     though it does run more slowly, and lacks the ability to capture substrings. On
170     the other hand, it does find all matches, not just the first, and it works
171     better for partial matching. The pcrematching man page discusses the
172     differences.
173    
174     The pcretest program has been enhanced so that it can make use of the new
175     pcre_dfa_exec() matching function and the extra features it provides.
176    
177     The distribution now includes a C++ wrapper library. This is built
178     automatically if a C++ compiler is found. The pcrecpp man page discusses this
179     interface.
180    
181     The code itself has been re-organized into many more files, one for each
182     function, so it no longer requires everything to be linked in when static
183     linkage is used. As a consequence, some internal functions have had to have
184     their names exposed. These functions all have names starting with _pcre_. They
185     are undocumented, and are not intended for use by outside callers.
186    
187     The pcregrep program has been enhanced with new functionality such as
188     multiline-matching and options for output more matching context. See the
189     ChangeLog for a complete list of changes to the library and the utility
190     programs.
191    
192    
193 nigel 75 Release 5.0 13-Sep-04
194     ---------------------
195    
196     The licence under which PCRE is released has been changed to the more
197     conventional "BSD" licence.
198    
199     In the code, some bugs have been fixed, and there are also some major changes
200     in this release (which is why I've increased the number to 5.0). Some changes
201     are internal rearrangements, and some provide a number of new facilities. The
202     new features are:
203    
204     1. There's an "automatic callout" feature that inserts callouts before every
205     item in the regex, and there's a new callout field that gives the position
206     in the pattern - useful for debugging and tracing.
207    
208     2. The extra_data structure can now be used to pass in a set of character
209     tables at exec time. This is useful if compiled regex are saved and re-used
210     at a later time when the tables may not be at the same address. If the
211     default internal tables are used, the pointer saved with the compiled
212     pattern is now set to NULL, which means that you don't need to do anything
213     special unless you are using custom tables.
214    
215     3. It is possible, with some restrictions on the content of the regex, to
216     request "partial" matching. A special return code is given if all of the
217     subject string matched part of the regex. This could be useful for testing
218     an input field as it is being typed.
219    
220     4. There is now some optional support for Unicode character properties, which
221     means that the patterns items such as \p{Lu} and \X can now be used. Only
222     the general category properties are supported. If PCRE is compiled with this
223     support, an additional 90K data structure is include, which increases the
224     size of the library dramatically.
225    
226     5. There is support for saving compiled patterns and re-using them later.
227    
228     6. There is support for running regular expressions that were compiled on a
229     different host with the opposite endianness.
230    
231     7. The pcretest program has been extended to accommodate the new features.
232    
233     The main internal rearrangement is that sequences of literal characters are no
234     longer handled as strings. Instead, each character is handled on its own. This
235     makes some UTF-8 handling easier, and makes the support of partial matching
236     possible. Compiled patterns containing long literal strings will be larger as a
237     result of this change; I hope that performance will not be much affected.
238    
239    
240 nigel 73 Release 4.5 01-Dec-03
241     ---------------------
242    
243     Again mainly a bug-fix and tidying release, with only a couple of new features:
244    
245     1. It's possible now to compile PCRE so that it does not use recursive
246     function calls when matching. Instead it gets memory from the heap. This slows
247     things down, but may be necessary on systems with limited stacks.
248    
249     2. UTF-8 string checking has been tightened to reject overlong sequences and to
250     check that a starting offset points to the start of a character. Failure of the
251     latter returns a new error code: PCRE_ERROR_BADUTF8_OFFSET.
252    
253     3. PCRE can now be compiled for systems that use EBCDIC code.
254    
255    
256 nigel 71 Release 4.4 21-Aug-03
257     ---------------------
258    
259     This is mainly a bug-fix and tidying release. The only new feature is that PCRE
260     checks UTF-8 strings for validity by default. There is an option to suppress
261     this, just in case anybody wants that teeny extra bit of performance.
262    
263    
264     Releases 4.1 - 4.3
265     ------------------
266    
267     Sorry, I forgot about updating the NEWS file for these releases. Please take a
268     look at ChangeLog.
269    
270    
271 nigel 63 Release 4.0 17-Feb-03
272     ---------------------
273    
274     There have been a lot of changes for the 4.0 release, adding additional
275     functionality and mending bugs. Below is a list of the highlights of the new
276     functionality. For full details of these features, please consult the
277     documentation. For a complete list of changes, see the ChangeLog file.
278    
279     1. Support for Perl's \Q...\E escapes.
280    
281     2. "Possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's Java
282     package. They provide some syntactic sugar for simple cases of "atomic
283     grouping".
284    
285     3. Support for the \G assertion. It is true when the current matching position
286     is at the start point of the match.
287    
288     4. A new feature that provides some of the functionality that Perl provides
289     with (?{...}). The facility is termed a "callout". The way it is done in PCRE
290     is for the caller to provide an optional function, by setting pcre_callout to
291     its entry point. To get the function called, the regex must include (?C) at
292     appropriate points.
293    
294     5. Support for recursive calls to individual subpatterns. This makes it really
295     easy to get totally confused.
296    
297     6. Support for named subpatterns. The Python syntax (?P<name>...) is used to
298     name a group.
299    
300     7. Several extensions to UTF-8 support; it is now fairly complete. There is an
301     option for pcregrep to make it operate in UTF-8 mode.
302    
303     8. The single man page has been split into a number of separate man pages.
304     These also give rise to individual HTML pages which are put in a separate
305     directory. There is an index.html page that lists them all. Some hyperlinking
306     between the pages has been installed.
307    
308    
309 nigel 53 Release 3.5 15-Aug-01
310     ---------------------
311    
312     1. The configuring system has been upgraded to use later versions of autoconf
313     and libtool. By default it builds both a shared and a static library if the OS
314     supports it. You can use --disable-shared or --disable-static on the configure
315     command if you want only one of them.
316    
317     2. The pcretest utility is now installed along with pcregrep because it is
318     useful for users (to test regexs) and by doing this, it automatically gets
319     relinked by libtool. The documentation has been turned into a man page, so
320     there are now .1, .txt, and .html versions in /doc.
321    
322     3. Upgrades to pcregrep:
323     (i) Added long-form option names like gnu grep.
324     (ii) Added --help to list all options with an explanatory phrase.
325     (iii) Added -r, --recursive to recurse into sub-directories.
326     (iv) Added -f, --file to read patterns from a file.
327    
328     4. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
329     script, to force use of CR or LF instead of \n in the source. On non-Unix
330     systems, the value can be set in config.h.
331    
332     5. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
333     absolute limit. Changed the text of the error message to make this clear, and
334     likewise updated the man page.
335    
336     6. The limit of 99 on the number of capturing subpatterns has been removed.
337     The new limit is 65535, which I hope will not be a "real" limit.
338    
339    
340 nigel 49 Release 3.3 01-Aug-00
341     ---------------------
342    
343     There is some support for UTF-8 character strings. This is incomplete and
344     experimental. The documentation describes what is and what is not implemented.
345     Otherwise, this is just a bug-fixing release.
346    
347    
348 nigel 43 Release 3.0 01-Feb-00
349     ---------------------
350 nigel 41
351 nigel 43 1. A "configure" script is now used to configure PCRE for Unix systems. It
352     builds a Makefile, a config.h file, and the pcre-config script.
353    
354     2. PCRE is built as a shared library by default.
355    
356     3. There is support for POSIX classes such as [:alpha:].
357    
358     5. There is an experimental recursion feature.
359    
360 nigel 41 ----------------------------------------------------------------------------
361     IMPORTANT FOR THOSE UPGRADING FROM VERSIONS BEFORE 2.00
362    
363     Please note that there has been a change in the API such that a larger
364     ovector is required at matching time, to provide some additional workspace.
365     The new man page has details. This change was necessary in order to support
366     some of the new functionality in Perl 5.005.
367    
368     IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.00
369    
370     Another (I hope this is the last!) change has been made to the API for the
371     pcre_compile() function. An additional argument has been added to make it
372     possible to pass over a pointer to character tables built in the current
373     locale by pcre_maketables(). To use the default tables, this new arguement
374     should be passed as NULL.
375    
376     IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.05
377    
378     Yet another (and again I hope this really is the last) change has been made
379     to the API for the pcre_exec() function. An additional argument has been
380     added to make it possible to start the match other than at the start of the
381     subject string. This is important if there are lookbehinds. The new man
382     page has the details, but you just want to convert existing programs, all
383     you need to do is to stick in a new fifth argument to pcre_exec(), with a
384     value of zero. For example, change
385    
386     pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)
387     to
388     pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)
389    
390     ****

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